Pump pressure control switches have long been used in applications such as home water wells. The switch includes a pressure chamber connected to the pressurized water system, e.g., to the pressure tank connected to the pump. When the pressure falls below a predetermined level, the switch turns the pump on, and turns it off again when a preset maximum pressure is reached. The control differential is the difference in pressure between these two points.
Known pump control switches are generally mounted in one of two ways. In one, the control is mounted directly to the tank, and a cord or electrical conduit and wiring are then run to the pump motor's wiring compartment. In the other, the control switch is mounted to the outside of the motor's wiring compartment, and the pressure connection to the water system is made via a hose or tubing, with electrical wiring run through the mounting connector.
Known pump controls generally include a pressure chamber wherein a diaphragm moves in response to changes in pressure. A spring-loaded switch mechanism including an actuator connected to the diaphragm causes the switch to bridge the electrical contacts at the predetermined minimum pressure. See Lindsey et al., U.S. Pat. No. 4,868,356, issued Sep. 19, 1989, Bodnar, U.S. Pat. No. 4,200,775, issued Apr. 29, 1980, Rice, U.S. Pat. No. 4,081,636, issued Mar. 28, 1978, Willcox, U.S. Pat. No. 4,054,763, issued Oct. 18, 1977, Willcox, U.S. Pat. No. 3,875,358, issued Apr. 1, 1975, Krieger et al., U.S. Pat. No. 3,773,991, issued Nov. 20, 1973, Weber, U.S. Pat. No. 3,335,241, issued Aug. 8, 1967, Parmann et al., U.S. Pat. No. 3,236,963, issued Feb. 22, 1966, and Krieger, Sr., et al., U.S. Pat. No. 3,139,493, issued Jun. 30, 1964. Miller U.S. Pat. No. 4,709,126, issued Nov. 24, 1987, describes a pressure switch wherein a pair of leaves pivot in V-shaped grooves of an output element under the action of a spring holding the leaves to the output element.
A variety of mechanisms for such devices are known, but each suffers from various disadvantages. Some are large, cumbersome devices with a large pressure chamber, spring, etc. See, for example, U.S. Pat. No. 3,340,372. Others lack the capacity to operate large devices. All require secondary wiring from the switch to the terminal board of the pump motor.
The present invention provides a pressure switch that addresses these disadvantages.